Exemplary embodiments of the present invention relate to a circuit for transferring data.
FIG. 1 illustrates a data transfer circuit for transferring a data from point A to point C through point B in an integrated circuit.
Referring to FIG. 1, a driver 110 positioned at point A transfers an input data DATA inputted thereto to point B through a line 120, and a driver 130 positioned at point B transfers the input data DATA to point C through a line 140. This is a typical structure of a data transfer circuit which transfers data from point A to point C through point B. As the distance from point A to point B and the distance from point B to point C become longer, each of the data transfer circuits for line 120 and line 140 is designed to have a greater load and have a stronger driving force in the driver 110 and the driver 130.
Hereafter, current consumption occurring in the data transfer circuit is divided into three cases and each case is described below.
Case 1
When an input data DATA input to the driver 110 is (H,L,H,L) in sequence, the data on each of lines 120 an 140 become (H,L,H,L) in sequence. Herein, to make data transitions on lines 120 and 130, significant current consumption occurs in both of the drivers 110 and 130. Thus, when a data pattern of (H,L,H,L) in sequence is used, significant current consumption occurs in data transfer circuits. Conditions deteriorate as the distances from point A to point B and the distance from point B to point C become longer.
Case 2
When the input data DATA input to the driver 110 are either (H,H,H,H) or (L,L,L,L) in sequence, the data on lines 120 and 140 do not transition. Since the data DATA do not transition, the current consumption in the driver 110 and the driver 130 is relatively small.
Case 3
When the input data DATA input to the driver 110 are (H,H,L,L) in sequence, the data on each of lines 120 and 140 become (H,H,L,L) in sequence. In this case, the number of data transitions is smaller than in Case 1 but larger than in Case 2. Therefore, the data transfer circuit in Case 3 consumes less current than that of Case 1 and more than that of Case 2.
As apparent from Cases 1, 2 and 3, the amount of current consumed in the conventional data transfer circuit may vary greatly according to a pattern of data transferred in the data transfer circuit. As such, the peak current of the data transfer circuit also greatly depends on the data pattern.
In many data transfer circuits, the total current consumption and the peak current of an integrated circuit is a significant performance criterion. When the peak current of the integrated circuit is relatively strong, a considerable amount of noise, power shortage, etc may occur.
An integrated circuit may include many data transfer circuits. However, the peak current consumed by the conventional data transfer circuit varies greatly depending on the data pattern. Therefore, a technology that can reduce the peak current of a data transfer circuit may be useful.